Cutting head for a water jet cutting assembly

ABSTRACT

An improved cutting head for a water jet cutting assembly utilizing water or other liquid medium at ultra high pressure, with the cutting head including an assembly with an elongated body having a central bore along its axis and including a delivery nozzle at the distal end of the assembly. Alignment of the components is maintained by incorporating a process of manufacture which utilizes the formation of a single bore extending through the body so as to both form and maintain axial alignment of the components. The arrangement is further characterized by having mating surfaces which are free of gaskets or other packing material, thereby establishing, maintaining, and preserving proper axial alignment of components.

FIELD OF THE INVENTION

The present invention relates generally to an improved system for fluidjet cutting machines having cutting heads for producing a high velocityfluid jet for penetrating and cutting through a workpiece. Morespecifically, the present invention relates to such a cutting headhaving means for introducing an abrasive particulate material into theflow, and additionally is configured in a manner permitting ease ofassembly and alignment of the flow channel as it extends through thecutting head, including that portion of the flow passing through theabrasive mixing chamber.

Water jet cutting machines are widely used for operation in cuttingand/or forming patterns in metallic, glass, ceramic, and othermaterials. Water jet cutting systems and machines have particularutility in connection with articles fabricated or formed of materialshaving brittle or poor mechanical properties. Additionally, water jetcutting systems have been found highly useful in connection with theformation of intricate or complex patterns without the creation of burrsor other anomalies requiring post-cutting treatment. As such, water jetcutting systems are highly useful in a wide variety of applications.

In connection with the cutting head portion of the system, a number ofsuch devices have been known in the past. Among these are that devicedisclosed in Chalmers U.S. Pat. No. 5,018,670, commonly assigned, andthe substance of which patent is hereby incorporated by reference.

In order to facilitate ease of assembly and alignment of the cuttinghead, the present invention is provided with components havingconfigurations which simplify alignment of the components of the flowchannel through the cutting head, and furthermore simplify the formationof seals between mating surfaces of individual components.

With the system of the present invention, a cutting head is providedwhich creates a water jet into which a suspension of abrasiveparticulate material has been introduced. Introduction of abrasivematerials increases the rate at which workpieces may be cut andfinished. For example, fluid jet cutting systems employ pumpscharacterized as intensifiers which increase the pressure of water inthe system to the ultra-high level, such as in the range of 60,000 psi.This high pressure water is forced through a jewel nozzle having a smallorifice therein in order to generate a jet flow of high velocity. Theabrasive materials are added to the flow downstream from the orifice ina mixing chamber, at which point the abrasive material is entrained intothe flow stream of the water jet. Upon leaving the mixing chamber, theflow stream enters and passes through a nozzle from which theabrasive-ladened flow exits the system. The nozzle assists in directingthe jet along its path toward the workpiece.

In order to extend the lifetime of the individual components, it isessential that the components through which the flow forming the waterjet passes be in proper axial alignment. Component misalignment canresult in damage to the bores, and such damage is typically immediateand extensive. Accordingly, it is important that alignment befacilitated and maintained.

The formation of seals between mating surfaces of components is also ofimportance. In the past, various added components are utilized to createseals. In the present invention, however, mating surfaces are providedwhich are machined to an appropriate tolerance so that the surfaces arecapable of withstanding the forces imposed by the ultra high pressurewater, and hence seals are formed without the necessity of addedcomponents such as "O"-rings and the like.

In order to create the initial alignment which is readily maintained,the body of the cutting head is bored axially from end-to-end,specifically from the inlet end to the outlet end. A counterbore isformed adjacent the inlet end, with the base of the counterbore forminga shoulder surface. This shoulder surface assists in aligning a jeweledseat assembly therewithin, and the presence of the elongated borethrough the body assures appropriate alignment of the components alongthe axis of the bore so formed.

SUMMARY OF THE INVENTION

In accordance with the present invention, a cutting head is provided fora water jet cutting system or assembly, with the cutting head comprisingan elongated body having an axially extending main bore therethrough,along with a counterbore extending through a portion of the length ofthe elongated body. An inlet is adjacent one end of the counterbore,with an outlet being provided at the opposed end of the body. A mixingchamber is interposed between the inlet and outlet ends, and a jeweledseat assembly is mounted on the shoulder formed at the base of thecounterbore. The jeweled seat assembly comprises a cylindrical body witha flanged head, and having a bore extending therethrough. A jewelreceiving cavity is formed in the head of the jeweled seat assembly,with the underside of the head of the jewel seat assembly forming a sealwith the base of the counterbore. The flow channel is formed by thejewel, and extends through the body, passing through the mixing chamberfrom which abrasive particulate may be introduced into the flow. Anozzle is mounted within the bore of the body, with the nozzle having aflow receiving bore arranged coaxially therewithin, with the nozzlebeing ultimately retained within the bore formed through the body. Inthis arrangement, therefore, the individual components are assembled insuch a way that effective seals are provided along mating surfaces, andfurthermore the fabrication techniques employed facilitate ease of bothinitial alignment and means for retaining alignment of componentsforming the flow channel formed by the jeweled orifice and extendingthrough the entire assembly including the nozzle discharge tip.

Therefore, it is a primary object of the present invention to provide animproved water jet cutting head having components formed and configuredin a fashion which facilitates ease of alignment during assembly, andwith the alignment being effectively retained.

It is a further object of the present invention to provide an improvedwater jet cutting head having components designed and configured topreserve axial alignment over extended periods of time, with the cuttinghead being further provided with a mixing chamber permitting theeffective introduction of abrasive particulate into the flow.

Other and further objects of the present invention will become apparentto those skilled in the art upon a study of the following specification,appended claims, and accompanying drawings.

IN THE DRAWINGS

FIG. 1 is a sectional view of the water jet cutting head of the presentinvention, and being taken along the line 1--1 of FIG. 2;

FIG. 2 is a top plan view of the water jet cutting head of the presentinvention;

FIG. 3 is a detail sectional view of the inlet adaptor of the presentinvention;

FIG. 4 is an enlarged sectional view of the jeweled seat assemblyemployed in connection with the present invention;

FIG. 5 is a perspective view of the insert component forming the mixingchamber of the cutting head of the present invention; and

FIG. 6 is a detail sectional view, on a slightly enlarged scale andpartially cut away, and illustrating that portion of the body of thecutting head into which the insert comprising the mixing chamber isplaced.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In accordance with the preferred embodiment of the present invention,and with particular attention being directed to FIGS. 1 and 2, the waterjet cutting head generally designated 10 includes a body member 11 withthe assembly having an inlet formed as at 12, and a nozzle component 13with an outlet 14. The entire assembly is arranged along a common axis,with the axis being shown at 16, and with each of the components alongthe flow path being positioned appropriately in axially alignedrelationship with an internal bore, such as bore 17. It will be notedthat axis 16 extends continuously through the components forming theassembly of the cutting head 10, and further that a counterbore isformed within body 11 as at 18. Counterbore 18 is, of course, in axialalignment with axis 16.

A jeweled seat assembly is shown at 19, with the jeweled seat assemblyfurther having a cavity formed therewithin to receive jeweled orifice20. A jewel having an orifice therethrough is referred to herein as a"jeweled orifice". Jeweled seat assembly 19 is formed with a headportion 21 having an undersurface 22 in mating relationship with thesurface forming the base of counterbore 18.

As is apparent, jeweled seat assembly 19 (FIG. 4) is arranged coaxiallywithin body 11, with seat assembly 19 being held in place by the forwardend of head of adaptor 24, with gland nut 25 being utilized to sealinglyforce and retain jeweled orifice assembly 19 in body 11.

Bore 17 is continuous and passes through body 11, and the cylindricalportion of jeweled orifice assembly 19 is received within a segment ofthis bore. Jeweled seat assembly 19 is further provided with an internalbore 26 which forms, along with jewel orifice 20, a portion of the flowpath which extends entirely through the member 10.

A mixing chamber is formed within the assembly as at 28, with the mixingchamber being, in turn, formed within cylindrical insert 29. Cylindricalinsert 29 has a "T"-shaped bore 30 formed therewithin including a basesegment along the axis of insert 29 and a cross segment extendingtransversely thereof. The intersection between the leg segment and crosssegment, in turn, defines the zone of mixing chamber 28. Inlet nut 31 isthreadably engaged in body 11 and is utilized to apply retention forceagainst insert 29 for retention within the bore 32 formed in body 11.

Nozzle 13 is retained within collet segment 34 of body 11. Colletsegment 34 is provided with threads to receive lock nut 35 thereon tofunction as a collet retainer. Nozzle 13 is accordingly maintainedwithin the bore extension of body 11 as at 17A.

In order to threadably couple lock nut 35 onto the base or distal end ofbody 11, particularly at and about the segments 36 forming collet 34,lock nut or collet retainer 35 along with the outer surface of thesegments 36 forming collet 34 are equipped with N.P.T. threads. Thisarrangement, and the mating conical configuration of the male and femaleportions forming the joint ensure that nozzle 13 is effectively retainedcoaxially within bore 17A of body 11.

In forming the bore 17 including its portion 17A, a single through-holeis bored within body 11 in a single operation. Thus, any deflection ormisalignment is effectively eliminated. The result is a "zero" tolerancearrangement with the assembly winding up in axially aligned relationshipupon completion of the assembly.

As has been indicated, mixing chamber 28 is formed within insert 29.Insert 29 is provided with an orientation indicating slot as at 29A.This slot is formed externally and visible to the technician throughcross-bore 38 extending through body 11. Thus, during assembly,appropriate alignment is achieved for insert 29 within body 11, withretention being obtained, as previously indicated, by threadablyengaging inlet nut retainer 31 within body 11. Suitable means, as areknown in the art, are utilized to couple inlet nut 31 to an appropriatesource of abrasive particulate. This arrangement has been found toprovide enhanced vacuum for control of abrasive feed rates, as well asreduction of turbulence and wear within the mixing chamber.

As has been indicated, a flow channel is provided through thelongitudinal extent of body 11. The orifice of jeweled orifice 20 has adiameter which is appropriate for diameters of the flow formedtherefrom. By way of example, the following relationship of orificediameter to flow and nozzle diameters are recommended:

    ______________________________________                                               Orifice                                                                             Flow/Nozzle                                                      ______________________________________                                               .008  .020                                                                    .010  .030                                                                    .015  .045                                                             ______________________________________                                    

In this connection, therefore, the devices are generally provided with aratio of diameters from orifice to flow channel of about 2.5:1 to 3:1.

The seals created between mating surfaces of the components are suchthat tendencies for galling are effectively eliminated, thusfacilitating both initial assembly and subsequent disassembly forpurposes of servicing the head.

It will be appreciated of course that various modifications may be madeto the specific structure set forth hereinabove without departing fromthe spirit and scope of the invention.

What is claimed is:
 1. A cutting head for a water jet cutting assemblycomprising, in combination:(a) an elongated body having a central axis,a main bore coaxial with said central axis, a counterbore having a flatannular surface at the base thereof, an inlet adjacent said counterborealong with an outlet disposed in opposed relationship to said inlet, anda mixing chamber interposed between said inlet and outlet; (b) a jeweledorifice assembly including a mounting shoulder mounted upon said flatannular surface, said jeweled orifice assembly comprising a cylindricalbody with a flanged head and a jewel receiving cavity within saidflanged head and positioned coaxially with said main bore for mounting ajeweled orifice adjacent said inlet, a flow channel formed within saidjeweled orifice assembly and extending from said assembly toward saidoutlet and arranged coaxially with said main bore; (c) the flanged headof said jeweled orifice assembly having an undersurface in planar matingrelationship with said flat annular surface; (d) an inlet adaptorpositioned coaxially within said counterbore and having a flangedforward head disposed in opposed relationship to said jeweled orificeassembly and with the said flanged forward head having a planar surfacein mating contact with the outer surface of the flanged head of saidjeweled orifice assembly; (e) the bore within said body adjacent saidoutlet having a nozzle member retained therewithin, the nozzle memberhaving a bore formed concentrically therethrough for receiving a flow ofwater from the bore of said jeweled orifice assembly, and means forretaining said nozzle member coaxially within said main bore, saidretaining means including mating conically configured threaded surfaces.2. The cutting head for a water jet cutting assembly as defined in claim1 being particularly characterized in that a mixing chamber ispositioned within said body, said mixing chamber being enclosed within acylindrical insert member having a "T" bore formed therewithin, and withthe mixing chamber being disposed adjacent the intersection of the legand cross bore segments of said "T", and with the leg segment of said"T" bore being adapted to receive a charge of abrasive for introductioninto said mixing chamber.
 3. The cutting head for a water jet cuttingassembly as defined in claim 2 being particularly characterized in thatmeans are provided for orienting the position of said cross bore segmentwithin said body.
 4. The cutting head for a water jet cutting assemblyas defined in claim 1 being particularly characterized in that means areprovided for forcibly retaining said jeweled orifice assembly againstthe surface of said adaptor to form a seal zone between mating surfacesof said jeweled orifice assembly and said inlet adaptor and between themating surfaces of the jeweled orifice assembly and said cross boresegment.
 5. The cutting head for a water jet cutting assembly as definedin claim 1 being particularly characterized in that the outlet of saidbody is disposed along a conically shaped distal tip portion of saidbody.